Strain rate sensitivity of five 3D printed polymer materials
Hari Bahadur Dura, Paul J. Hazell, Hongxu Wang, J. P. Escobedo, Jianshen Wang
Abstract
The strain rate sensitivity on the uniaxial compressive response of five 3D printed polymer-based materials was investigated. Five commonly used polymers – acrylonitrile butadiene styrene (ABS), nylon, polylactic acid (PLA), toughened polylactic acid (TPLA), and thermoplastic polyurethane (TPU) – were studied. Cylindrical specimens (Ø8 mm × 8 mm) were printed using an Ultimaker S5 3D printer, with a print layer height of 0.1 mm and identical print paths. The manufacturing quality of the 3D-printed specimens was assessed using X-ray computed tomography (CT) at a resolution of 27 μm. Among the materials tested, TPU and nylon exhibited the highest levels of porosity. Low-strain rate tests ranging from 10 -3 /s to 1/s were carried out using a universal testing machine, while tests at strain rates above 1/s were conducted with a split-Hopkinson pressure bar. All five polymers exhibited positive strain rate sensitivity. The strain rate coefficients in the Johnson-Cook (J-C) material model were 0.049, 0.072, 0.071, 0.073, and 0.625 for ABS, nylon, PLA, TPLA, and TPU, respectively. The J-C model successfully captured the strain rate effects for ABS, PLA, TPLA, and nylon but failed to capture the low strain rate behaviour for TPU.